고력볼트의 축력-토크 상관관계를 규명하기 위한 체결특성 평가실험과 시간의 경과에 의한 볼트의 축력감소를 검증하기 위하여 장기축력이완 실험을 실시하였다. 또한 도입축력과 볼트구멍 크기 변화, 부재의 표면상태 등에 따른 고력볼트 마찰접합부의 구조적 거동을 분석하였다. 마찰접합부의 미끄럼내력에 영향을 미치는 다양한 변수를 적용한 실험·해석을 통하여 고력볼트 체결 및 마찰접합부 관련 국내 설계기준·규정 및 연구개발에 대한 기술정보를 제공하고자 한다. (1) 토크계수 변화에 의한 고력볼트 축력저하 실험결과 수분침적 조건에서 토크계수 상승에 의해 18~36%의 도입축력이 저하됨을 확인하였다. 볼트 규격에 따른 축력저하율 비교에서 2% 이내의 차이를 보였으며, 볼트 종류에 따른 비교에서 육각고력볼트가 ...
고력볼트의 축력-토크 상관관계를 규명하기 위한 체결특성 평가실험과 시간의 경과에 의한 볼트의 축력감소를 검증하기 위하여 장기축력이완 실험을 실시하였다. 또한 도입축력과 볼트구멍 크기 변화, 부재의 표면상태 등에 따른 고력볼트 마찰접합부의 구조적 거동을 분석하였다. 마찰접합부의 미끄럼내력에 영향을 미치는 다양한 변수를 적용한 실험·해석을 통하여 고력볼트 체결 및 마찰접합부 관련 국내 설계기준·규정 및 연구개발에 대한 기술정보를 제공하고자 한다. (1) 토크계수 변화에 의한 고력볼트 축력저하 실험결과 수분침적 조건에서 토크계수 상승에 의해 18~36%의 도입축력이 저하됨을 확인하였다. 볼트 규격에 따른 축력저하율 비교에서 2% 이내의 차이를 보였으며, 볼트 종류에 따른 비교에서 육각고력볼트가 TS 고력볼트에 비해 수분침적에 의한 축력저하가 민감한 것으로 파악되었다. (2) 고력볼트는 이음부의 장기축력이완 실험결과 체결초기인 168시간의 경우 2.76~8.59%의 축력이 저하되었으며 체결 후 500시간 경과 후 3.19~9.55%의 축력이 저하되었다. 체결시간 경과에 의한 비교결과 총 저하량의 88%의 축력이 168시간 이내 저하되어 체결 초기에 볼트의 축력확보 및 유지가 중요한 것으로 판단된다. (3) 고력볼트의 도입축력 변화에 의한 실험결과 저하된 도입축력의 저하량과 비례적으로 마찰이음부의 미끄럼내력이 21~40% 감소하였다. 고력볼트의 구멍크기 변화에 의한 실험결과 볼트구멍이 과대해짐에 따라 이음부의 미끄럼내력과 미끄럼계수가 11~13% 감소하였다. (4) 유한요소해석을 통한 마찰이음부의 거동파악 결과 볼트의 축력만 저하될 때에는 16%~43%의 미끄럼내력이 감소하고, 볼트의 축력과 볼트구멍크기가 변화가 동시에 적용될 때에는 11%~52%의 미끄럼내력이 감소하였다. 도입축력 변화조건 실험체 경우 미끄럼내력만 감소되었으며 볼트구멍 크기가 변화하는 경우 과대크기만큼 미끄럼발생 변위와 지압시점 변위가 커졌다.
고력볼트의 축력-토크 상관관계를 규명하기 위한 체결특성 평가실험과 시간의 경과에 의한 볼트의 축력감소를 검증하기 위하여 장기축력이완 실험을 실시하였다. 또한 도입축력과 볼트구멍 크기 변화, 부재의 표면상태 등에 따른 고력볼트 마찰접합부의 구조적 거동을 분석하였다. 마찰접합부의 미끄럼내력에 영향을 미치는 다양한 변수를 적용한 실험·해석을 통하여 고력볼트 체결 및 마찰접합부 관련 국내 설계기준·규정 및 연구개발에 대한 기술정보를 제공하고자 한다. (1) 토크계수 변화에 의한 고력볼트 축력저하 실험결과 수분침적 조건에서 토크계수 상승에 의해 18~36%의 도입축력이 저하됨을 확인하였다. 볼트 규격에 따른 축력저하율 비교에서 2% 이내의 차이를 보였으며, 볼트 종류에 따른 비교에서 육각고력볼트가 TS 고력볼트에 비해 수분침적에 의한 축력저하가 민감한 것으로 파악되었다. (2) 고력볼트는 이음부의 장기축력이완 실험결과 체결초기인 168시간의 경우 2.76~8.59%의 축력이 저하되었으며 체결 후 500시간 경과 후 3.19~9.55%의 축력이 저하되었다. 체결시간 경과에 의한 비교결과 총 저하량의 88%의 축력이 168시간 이내 저하되어 체결 초기에 볼트의 축력확보 및 유지가 중요한 것으로 판단된다. (3) 고력볼트의 도입축력 변화에 의한 실험결과 저하된 도입축력의 저하량과 비례적으로 마찰이음부의 미끄럼내력이 21~40% 감소하였다. 고력볼트의 구멍크기 변화에 의한 실험결과 볼트구멍이 과대해짐에 따라 이음부의 미끄럼내력과 미끄럼계수가 11~13% 감소하였다. (4) 유한요소해석을 통한 마찰이음부의 거동파악 결과 볼트의 축력만 저하될 때에는 16%~43%의 미끄럼내력이 감소하고, 볼트의 축력과 볼트구멍크기가 변화가 동시에 적용될 때에는 11%~52%의 미끄럼내력이 감소하였다. 도입축력 변화조건 실험체 경우 미끄럼내력만 감소되었으며 볼트구멍 크기가 변화하는 경우 과대크기만큼 미끄럼발생 변위와 지압시점 변위가 커졌다.
A torque characteristic assessment test to determine the relation between axial force of high strength bolts and torque, and an axial force laxity test to verify the axial force reduction in a bolt in terms of time were conducted. And the structural behavior was analyzed for the friction joints of h...
A torque characteristic assessment test to determine the relation between axial force of high strength bolts and torque, and an axial force laxity test to verify the axial force reduction in a bolt in terms of time were conducted. And the structural behavior was analyzed for the friction joints of high strength bolts depending on the axial force, changes in hole size of bolt and surface condition of the material through experiments and analysis. This study was conducted to provide technical information on design standard, regulation and R&D regarding the high strength bolt torque and friction joints through experiments and analyses with application of various variables influencing the slip load of friction joints. (1) As the result of axial force reduction in high strength bolts due to changes in torque factor, 18-36% reduction in the axial force was observed due to increased torque factor under the condition of immersion in water. In comparison with the axial force reduction due to bolt dimension, the change was within 2%. In comparison with axial force reduction due to bolt types, hexagonal high strength bolts showed more sensitive changes in axial force reduction in immersion in water than the TS high strength bolts. In addition, TS bolt pin tail had fractured at certain torque regardless of reduction in axial force so that a consideration was required in securing axial force in TS high strength bolts with changes in torque factor. (2) As the result of axial force laxity test on the joint of high strength bolts, the rate of axial force reduction was 2.76-8.59% in initial 168 hours and 3.19~9.55% in 500 hours. The axial force laxity in long term progressed in constant value regardless of dimension of bolt, and the axial force reduction of hexagonal high strength bolts in term of time was observed to be greater than TS high strength bolts torqued by the pin tail. As the result of comparison as the time went, total reduction rate was 88% within first 168 hours so that it is important to maintain the axial force of bolt in initial stage. (3) As the result of testing changes in initial axial force of high strength bolts, the reduction rate in slip load in joints was 21-40% which was proportion to the reduction of initial axial force. However, it did not influence the slip factor and maximum load. In a test with 0% axial force, there was the slip only associated with increased displacement without any change in load which implied the functionality of slip joint was lost. As the result of testing changes due to hole size of high strength bolts, the slip load and slip factor reduction rate in joint was 11-13% as the bolt hole got larger. (4) Through finite element analysis, behavior was investigated with application of combinational variables depending on bolt hole size and initial axial force changes in friction joints by surface conditions. With only the axial force reduction, the slip load reduction rate was 16-43%. With simultaneous changes of axial force and bolt hole size, the slip load reduction rate was 11-52%. In the case of initial axial force change only, it behaved normal and only the slip load was reduced. In the case of bolt hole size changes, the slip displacement and pressure point displacement were greater with excessive size. As the result of test by different surface conditions with identical initial axial force, the slip load changed in proportion to the slip factor.
A torque characteristic assessment test to determine the relation between axial force of high strength bolts and torque, and an axial force laxity test to verify the axial force reduction in a bolt in terms of time were conducted. And the structural behavior was analyzed for the friction joints of high strength bolts depending on the axial force, changes in hole size of bolt and surface condition of the material through experiments and analysis. This study was conducted to provide technical information on design standard, regulation and R&D regarding the high strength bolt torque and friction joints through experiments and analyses with application of various variables influencing the slip load of friction joints. (1) As the result of axial force reduction in high strength bolts due to changes in torque factor, 18-36% reduction in the axial force was observed due to increased torque factor under the condition of immersion in water. In comparison with the axial force reduction due to bolt dimension, the change was within 2%. In comparison with axial force reduction due to bolt types, hexagonal high strength bolts showed more sensitive changes in axial force reduction in immersion in water than the TS high strength bolts. In addition, TS bolt pin tail had fractured at certain torque regardless of reduction in axial force so that a consideration was required in securing axial force in TS high strength bolts with changes in torque factor. (2) As the result of axial force laxity test on the joint of high strength bolts, the rate of axial force reduction was 2.76-8.59% in initial 168 hours and 3.19~9.55% in 500 hours. The axial force laxity in long term progressed in constant value regardless of dimension of bolt, and the axial force reduction of hexagonal high strength bolts in term of time was observed to be greater than TS high strength bolts torqued by the pin tail. As the result of comparison as the time went, total reduction rate was 88% within first 168 hours so that it is important to maintain the axial force of bolt in initial stage. (3) As the result of testing changes in initial axial force of high strength bolts, the reduction rate in slip load in joints was 21-40% which was proportion to the reduction of initial axial force. However, it did not influence the slip factor and maximum load. In a test with 0% axial force, there was the slip only associated with increased displacement without any change in load which implied the functionality of slip joint was lost. As the result of testing changes due to hole size of high strength bolts, the slip load and slip factor reduction rate in joint was 11-13% as the bolt hole got larger. (4) Through finite element analysis, behavior was investigated with application of combinational variables depending on bolt hole size and initial axial force changes in friction joints by surface conditions. With only the axial force reduction, the slip load reduction rate was 16-43%. With simultaneous changes of axial force and bolt hole size, the slip load reduction rate was 11-52%. In the case of initial axial force change only, it behaved normal and only the slip load was reduced. In the case of bolt hole size changes, the slip displacement and pressure point displacement were greater with excessive size. As the result of test by different surface conditions with identical initial axial force, the slip load changed in proportion to the slip factor.
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